Next-generation HVAC: Prospects for and limitations of desiccant and membrane-based dehumidification and cooling

Abstract

Recently, next-generation HVAC technologies have gained attention as potential alternatives to the conventional vapor-compression system (VCS) for dehumidification and cooling. Previous studies have primarily focused on analyzing a specific technology or its application to a particular climate. A comparison of these technologies is necessary to elucidate the reasons and conditions under which one technology might outperform the rest. In this study, we apply a uniform framework based on fundamental thermodynamic principles to assess and compare different HVAC technologies fromGeneration HVAC: Prospects for and Limitations of Desiccant and Membrane-Based Dehumidification and Cooling," Applied Energy, 200:330-346, 15 August 2017.an energy conversion standpoint. The thermodynamic least work of dehumidification and cooling is formally defined as a thermodynamic benchmark, while VCS performance is chosen as the industry benchmark against which other technologies, namely desiccant-based cooling system (DCS) and membrane-based cooling system (MCS), are compared. The effect of outdoor temperature and humidity on device performance is investigated, and key insights underlying the dehumidification and cooling process are elucidated. In spite of the great potential of DCS and MCS technologies, our results underscore the need for improved system-level design and integration if DCS or MCS are to compete with VCS. Our findings have significant implications for the design and operation of next-generation HVAC technologies and shed light on potential avenues to achieve higher efficiencies in dehumidification and cooling applications.

Relating transport modeling to nanofiltration membrane fabrication: Navigating the permeability-selectivity trade-off in desalination pretreatment

“…Since the twentieth century, advances in membrane technology have been at the forefront of engineering innovations shaping humanity's standard of living worldwide [1]. From medical applications such as drug delivery and tissue engineering [2] to industrial applications, ranging from gas separation [3] and water purification [4] to humidity harvesting and dehumidification [5], the importance of membranes to achieving chemical separation or moderated chemical transport cannot be overstated.…”

Parametric analysis of a cross-flow membrane-based parallel-plate liquid desiccant dehumidification system: Numerical and experimental data

“…Huang et al [25,26] conducted several researches into an elliptical hollow fiber membrane tube bank, which is a more normal case in reality, the local and average Nusselt and Sherwood numbers under the conjugate heat and mass transfer boundary condition are obtained. Applications of membrane-based liquid desiccant humidification in real industry have also been reported [27][28][29].…”

Experimental Study on the Water Selective Dense Membrane under an Absolute Pressure Difference with Simplified Test Method

“…According to the report, membrane-based vacuum dehumidification (MVD) systems are expected to show higher efficiency than existing vapor compression cooling systems because they require less energy to remove the water vapor and avoid the environmental problems caused by refrigerants. Hence, several membrane heat pump designs with different MVD configurations have been presented, and their performance analyzed using various methods [3][4][5][6].…”

“…To date, a membrane model which assumes the concentration difference of the gas, i.e., vapor pressure difference as a sole driver of the mass transfer within the system has been used for performance analysis. Previous analytical studies of dense membranes often assumed that the selectivity was infinite, and they suggested several different types of MVD systems [3][4][5][6][7]. However, as the actual dense membrane will have a large but finite selectivity inevitably, the design and operation of should be reconsidered in practice.…”